Compositions containing poly(arylene ether)s and styrenic block copolymers are known and valued for their improved properties relative to either resin type alone. For example, U.S. Pat. No. 3,660,531 (Lauchlan) describes blends of polyphenylene ethers with styrene-butadiene block copolymers and teaches that the blends exhibit improved melt processability and impact resistance without sacrificing the desirable heat distortion temperature and flexural modulus of unmodified polyphenylene ether. As another example, U.S. Pat. No. 5,234,994 (Shiraki et al.) describes blends of a polyphenylene ether, a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene, and polystyrene. The blends are described as offering improved transparency, impact resistance, surface hardness, heat resistance, and gloss. As yet another example, U.S. Pat. No. 6,274,670 (Adedeji et al.) describes a composition comprising a polyphenylene ether resin, a non-elastomeric styrenic resin, and an unsaturated elastomeric styrenic block copolymer. When the non-elastomeric styrenic resin is a styrene-butadiene block copolymer having at least 50 weight percent styrene, these compositions are semi-transparent and exhibit enhanced processability.
Despite these advances, light color, low haze, impact-resistant, and flame-retardant poly(arylene ethers) remain an illusive target. Although optical enhancing agents along with flame-retardants can give resins with improved clarity and less haze, they also lead to resins with reduced impact resistance scores relative to resins without these additives.
There is therefore a need in the packaging and healthcare industries, among others, for poly(arylene ether) blends that exhibit an improved balance of optical clarity and impact resistance.